Re-usable medical devices such as certain surgical instruments, endoscopes, etc., may be sterilized before re-use in order to minimize the likelihood that a contaminated device might be used on a patient, which could cause an infection in the patient. Various sterilization techniques may be employed, such as steam, hydrogen peroxide, peracetic acid, and vapor phase sterilization, either with or without a gas plasma and ethylene oxide (EtO). Each of these methods may depend to a certain extent on the diffusion rates of the sterilization fluids (e.g., gases) upon or into the medical devices to be sterilized.
Before sterilization, medical devices may be packaged within containers or pouches having a semi-permeable barrier that allows transmission of the sterilizing fluid—sometimes referred to as a sterilant—but prevents admission of contaminating organisms, particularly post-sterilization and until the package is opened by medical personnel. For the sterilization cycle to be efficacious, the contaminating organisms within the package must be killed because any organisms that survive the sterilization cycle could multiply and re-contaminate the medical device. Diffusion of the sterilant may be particularly problematic for medical devices that have diffusion-restricted spaces therein because these diffusion-restricted spaces may reduce the likelihood that a sterilization cycle may be effective. For example, some endoscopes have one or more long narrow lumens into which the sterilant must diffuse in sufficient concentration for sufficient time to achieve a successful sterilization cycle.
Sterilization of medical devices may be performed with an automated sterilization system such as a STERRAD® System by Advanced Sterilization Products of Irvine, Calif. Examples of automated sterilization systems are described in U.S. Pat. No. 6,939,519, entitled “Power System for Sterilization Systems Employing Low Frequency Plasma,” issued Sep. 6, 2005, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,852,279, entitled “Sterilization with Temperature-Controlled Diffusion Path,” issued Feb. 8, 2005, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,852,277, entitled “Sterilization System Employing a Switching Module Adapter to Pulsate the Low Frequency Power Applied to a Plasma,” issued Feb. 8, 2005, the disclosure of which is incorporated by reference herein; U.S. Pat. No. 6,447,719, entitled “Power System for Sterilization Systems Employing Low Frequency Plasma,” issued Sep. 10, 2002, the disclosure of which is incorporated by reference herein; and U.S. Provisional Pat. App. No. 62/316,722, entitled “System and Method for Sterilizing Medical Devices,” filed Apr. 1, 2016, the disclosure of which is incorporated by reference herein.
Some sterilization systems may use vaporized chemical sterilants or chemical gas such as hydrogen peroxide, peracetic acid, ozone, chlorine dioxide, nitrogen dioxide, etc., to sterilize medical devices. Examples of such systems are described in U.S. Pat. No. 6,365,102, entitled “Method of Enhanced Sterilization with Improved Material Compatibility,” issued Apr. 2, 2002, the disclosure of which is incorporated by reference herein, and U.S. Pat. No. 6,325,972, entitled “Apparatus and Process for Concentrating a Liquid Sterilant and Sterilizing Articles Therewith,” issued Dec. 4, 2001, the disclosure of which is incorporated by reference herein. Some such systems provide a hydrogen peroxide/gas plasma sterilization system comprising a vacuum chamber and plasma source and increased concentration of hydrogen peroxide for sterilization. Some such systems may have difficulty sterilizing lumens of some medical devices if their length exceeds a certain value; or the processing time of such systems may still not be fast enough for some applications. Thus, some medical devices such as long and/or narrow flexible endoscopes may not be completely sterilized by these systems due to the insufficient reach of sterilant vapor to the inside of the channels. Such medical devices might therefore only be disinfected without being sterilized. Sterilization systems that use ethylene oxide may have a relatively long processing time (e.g., longer than 24 hours), which may be undesirable in some cases.
Operator error may result in medical devices that are erroneously believed to be decontaminated being returned to service. Confirming that a sterilization cycle has been efficacious may help medical personnel avoid using a contaminated medical device on a patient. The sterilized medical device might not itself be checked for contaminating organisms because such an activity may introduce other contaminating organisms to the medical device, thereby re-contaminating it. Thus, an indirect check may be performed using a sterilization indicator. A sterilization indicator is a device that may be placed alongside or in proximity to a medical device being subject to a sterilization cycle, such that the sterilization indicator is subject to the same sterilization cycle as the medical device. For instance, a biological indictor having a predetermined quantity of microorganisms may be placed into a sterilization chamber alongside a medical device and subject to a sterilization cycle. After the cycle is complete, the microorganisms in the biological indicator may be cultured to determine whether any of the microorganisms survived the cycle. The presence or absence of living microorganisms in the biological indicator will indicate whether the sterilization cycle was effective.
While a variety of systems and methods have been made and used for surgical instrument sterilization, it is believed that no one prior to the inventor(s) has made or used the technology as described herein.